flake8-iw 0.0.16

A plugin to show lint errors for IW

flake8-iw

Linters for some common issues we encounter.- flake8-iw

• Building and testing
• Supported lint checks
  • IW01: Use of patch
  • IW02: Use of patch for time freeze
  • IW03: Error logging without exception info (exc_info)
  • IW04: Use of datetime.now
  • IW05: Use of datetime.replace(tzinfo=XXX)
  • IW06: Use of bulk_update/bulk_create without batch_size

Building and testing

Run command to build wheel and tarball.

python3 -m build
twine check --strict dist/*
twine upload dist/*

Run command to test.

pytest

Supported lint checks

IW01: Use of patch

Lint check to prevent the use of patch directly. Recommendation: Use PatchingTestCase / PatchingTransactionTestCase instead

Correct ✅

from instawork.tests import PatchingTestCase


class SignUpUpdatedTests(PatchingTestCase):
    def setUp(self):
        self.mock_call = self.patch("apps.auth.signals.task_send_email.delay")

    def test_email(self):
        expect(self.mock_call).to(have_been_called_once)

    def test_sms(self):
        mock_sms = self.patch("apps.auth.signals.task_send_sms.delay")
        expect(mock_sms).to(have_been_called_once)

Wrong ⚠️

from unittest.mock import patch


class SignUpUpdatedTests(TestCase):
    def setUp(self):
        self.patcher = patch("apps.auth.signals.task_send_email.delay")
        self.mock_email = self.patcher.start()

    def tearDown(self):
        self.patcher.stop()

    def test_email(self):
        ...
        expect(self.mock_email).to(have_been_called_once)

    @patch("apps.auth.signals.task_send_sms.delay")
    def test_sms(self, mock_sms):
        ...
        expect(mock_sms).to(have_been_called_once)

IW02: Use of patch for time freeze

Lint check to prevent the use of patch to freeze time. Recommendation: Use freeze_time from PatchingTestCase / PatchingTransactionTestCase or use freeze_time decorator or context manager from freezegun package.

Correct ✅

from django.utils import timezone
from instawork.tests import PatchingTestCase


class UserFeatureViewTests(PatchingTestCase):
    def setUp(self):
        self.now = timezone.now()

    def test_feature_view(self):
        ufv = None

        # Option 1
        with freeze_time(self.now):
            ufv = UserFeatureView.objects.get_or_create(
                user=self.shift.worker, feature=UserFeatureView.FEATURE_1
            )

        # Option 2
        self.freeze_time(self.now)
        ufv = UserFeatureView.objects.get_or_create(
            user=self.shift.worker, feature=UserFeatureView.FEATURE_1
        )

        ...

        expect(ufv.date_created).to(equal(self.now))

Wrong ⚠️

from django.utils import timezone
from instawork.tests import PatchingTestCase


class UserFeatureViewTests(PatchingTestCase):
    def setUp(self):
        self.now = timezone.now()
        self.mock_call = self.patch("django.utils.timezone.now", return_value=self.now)

    def test_feature_view(self):
        ufv = UserFeatureView.objects.get_or_create(
            user=self.shift.worker, feature=UserFeatureView.FEATURE_1
        )

        ...

        expect(ufv.date_created).to(equal(self.now))

IW03: Error logging without exception info (exc_info)

Lint check to prevent error logging without exception info. Recommendation: Add exc_info=True keyword argument in logger.error()

Correct ✅

import logging

custom_logger = logging.getLogger("module.logger")

class UserFeatureView(Model):
    def save(self):
        try:
            ...
        except ValueError as e:
            custom_logger.error(e, exc_info=True)
            return name

Wrong ⚠️

import logging

custom_logger = logging.getLogger("module.logger")

class UserFeatureView(Model):
    def save(self):
        try:
            ...
        except ValueError as e:
            custom_logger.error(e)
            return name

IW04: Use of datetime.now

Lint to avoid usage of datetime.now() which does not contain timezone information and causes various warnings in tests. Use timezone.now() instead.

Correct ✅

from django.utils import timezone

now = timezone.now()

Wrong ⚠️

from datetime import datetime

now = datetime.now()

IW05: Use of datetime.replace(tzinfo=XXX)

Lint to avoid usage of datetime.replace(tzinfo=XXX) which is not a viable way of setting timezones with python/pytz.

Correct ✅

import pytz
from django.utils import timezone

tz = pytz.timezone("America/Los_Angeles")
now_pt = timezone.now().astimezone(tz)

Wrong ⚠️

import pytz
from django.utils import timezone

tz = pytz.timezone("America/Los_Angeles")
now_pt = timezone.now().replace(tzinfo=tz)

IW06: Use of bulk_update/bulk_create without batch_size

Lint to avoid usage of Model.objects.bulk_update / Model.objects.bulk_create. Use Model.objects.bulk_update(batch_size=X) / Model.objects.bulk_create(batch_size=X) instead.

Correct ✅

# Bulk update
Model.objects.bulk_update([obj1, obj2, ...], batch_size=10)

# Bulk create
Model.objects.bulk_create([obj1, obj2, ...], batch_size=10)

Wrong ⚠️

# Bulk update
Model.objects.bulk_update([obj1, obj2, ...])

# Bulk create
Model.objects.bulk_create([obj1, obj2, ...])

IW07: IW07 use of celery.shared_task, use instawork.decorators.shared_task

Use our internal decorator instead: instawork.decorators.shared_task.

Correct ✅

from instawork.decorators import shared_task

@shared_task
def my_task():
    pass

Wrong ⚠️

from celery import shared_task

@shared_task
def my_task():
    pass